The S-Phase Checkpoint Is Required To Respond to R-Loops Accumulated in THO Mutants
The S-Phase Checkpoint Is Required To Respond to R-Loops Accumulated in THO Mutants
复制标题
DOI：
10.1128/mcb.00402-09
复制
发表时间：
2009-10-01
影响因子：
5.3
通讯作者：
Aguilera, Andres
中科院分区：
文献类型：
--
作者：
Gomez-Gonzalez, Belen;Felipe-Abrio, Irene;Aguilera, Andres
共转录R-环在酵母THO复合体的突变体中形成，它在转录和mRNA输出之间的界面上发挥作用。尽管R-环在转录相关的重组中具有相关性，但它们触发重组的机制仍然不清楚。为了了解R-环如何影响基因组的稳定性，我们分析了THO与26个基因的遗传相互作用，这些基因涉及复制、S阶段检查点、DNA修复和染色质重塑。我们发现在THO和S期检查点因子的双零突变体中，如复制因子C和增殖细胞核抗原样复合体，存在合成生长缺陷。在复制胁迫下，形成R环的突变体需要功能性的S阶段的检查点功能，而不是双链断裂修复功能才能生存。此外，R-环形成的hpr1 Delta突变体在活跃转录的染色体区域表现出复制分叉进展障碍，并触发Rad53磷酸化。我们的结论是，R-环介导的DNA损伤激活了S阶段的检查点，这是复制胁迫下突变体细胞生存所必需的。根据这些结果，我们提出了一个模型，在该模型中，R环介导的重组可以通过模板切换来解释。
Cotranscriptional R-loops are formed in yeast mutants of the THO complex, which functions at the interface between transcription and mRNA export. Despite the relevance of R-loops in transcription- associated recombination, the mechanisms by which they trigger recombination are still elusive. In order to understand how R-loops compromise genome stability, we have analyzed the genetic interaction of THO with 26 genes involved in replication, S-phase checkpoint, DNA repair, and chromatin remodeling. We found a synthetic growth defect in double null mutants of THO and S-phase checkpoint factors, such as the replication factor C- and PCNA-like complexes. Under replicative stress, R-loop-forming THO null mutants require functional S-phase checkpoint functions but not double-strand-break repair functions for survival. Furthermore, R-loop-forming hpr1 Delta mutants display replication fork progression impairment at actively transcribed chromosomal regions and trigger Rad53 phosphorylation. We conclude that R-loop-mediated DNA damage activates the S-phase checkpoint, which is required for the cell survival of THO mutants under replicative stress. In light of these results, we propose a model in which R-loop-mediated recombination is explained by template switching.